The invention relates to an apparatus at a spinning preparation machine, for example a cleaner, opener, carding machine or the like, for detecting waste which is separated out from fibre material, for example cotton.
The fibre material typically consists of foreign matter and good fibres, and may be collected in a collecting device, wherein there is provided an optical measuring device having a brightness sensor, which measuring device examines the waste. In a known apparatus (EP-A-0 399 315), the beater pins of a cleaning roller convey the fibre flocks over cleaning bars which are adjustable so that the intensity of cleaning can be varied. Below the cleaning bars, a brightness sensor measures the brightness as a measure of the contaminant content of the offtake (waste), which has been separated out by the cleaning bars and is collected in a funnel-like collecting device. At prespecified time intervals, the offtake is drawn off under suction by way of a suction conveyor arranged at the lower end of the collecting device. The brightness—measured by the brightness sensor—of the separated-out waste, in the form of a signal, is input into a control system and displayed on a display. One disadvantage is that the sensor serves only for detecting the contaminant content; the content of good fibres is not detected. It is furthermore disadvantageous that the determined degree of cleaning is investigated, by sensors, in the offtake chamber of the cleaning machine. Finally, the brightness, that is to say the degree of brightness—measured by the sensor—of the offtake is merely input into the control system without, however, any optimum operating point of the cleaning machine being derived therefrom.
It is an aim of the invention to provide an apparatus of the kind described at the beginning which avoids or mitigates the mentioned disadvantages and which especially makes it possible for the content of good fibres in the offtake to be detected by simple means and allows optimum adjustment of the composition of the offtake, especially to have a high content of foreign matter (trash) and a low content of good fibres.